Generally, light absorbing compounds are introduced into a silver halide emulsion layer or other hydrophilic colloid layers of a multilayer color light-sensitive material to absorb light of a specific wavelength for sensitivity adjustment, improvement in safelight characteristics, color temperature adjustment of light, prevention of halation, and adjustment of sensitivity balance.
For example, when a silver halide photographic light-sensitive material, which comprises a support having thereon one or more hydrophilic layers such as a light-sensitive silver halide emulsion layer, is subjected to imagewise exposure, it is necessary to control the spectral composition of light incident to the silver halide emulsion layers in order to improve photographic sensitivity. In this case, a dye which absorbs light of a wavelength not used for imaging the silver halide emulsion layer is incorporated into the hydrophilic colloid layers farther from the support than the light-sensitive silver halide emulsion layer to form a filter layer. Light of the desired imaging wavelength alone is transmitted through the filter layer.
An anti-halation layer used to improve the sharpness of an image is provided between a light-sensitive layer and a support or on the backside of the support, to absorb harmful reflected light at the boundary between the emulsion layer and support and on the backside of the support.
Furthermore, a dye which absorbs light in the wavelength region in which silver halide is sensitive is used on occasion to prevent irradiation of a silver halide emulsion layer, to improve the sharpness of the resulting image.
Particularly, a silver halide photographic light-sensitive material for plate making which is used in a light room contains a dye which absorbs UV rays and visible rays in a light-sensitive layer or a layer arranged between the light source and light-sensitive layer to provide increased protection to a safelight.
Furthermore, in an X-ray light sensitive material, a coloring layer may be provided to improve sharpness by decreasing crossover.
The layers to be colored are generally composed of a hydrophilic colloid, and therefore a dye is usually incorporated into the coloring layers. This dye desirably satisfies the following conditions:
(1) appropriate spectral absorption according to the intended use;
(2) photochemically inactive, namely, not adversely affecting the photographic characteristics of a silver halide photographic layer with respect to, for example, sensitivity, latent image stability and fogging;
(3) bleached, dissolved and removed in photographic processing steps without staining a processed photographic light-sensitive layer; and
(4) excellent aging stability in a coating liquid (solution) or a silver halide photographic material, with no variation in quality.
Much effort has been made by prior investigators to develop dyes satisfying these requirements. Examples thereof include the pyrazolone oxonol dye described in British Patent 506,385, the barbituric acid oxonol dye described in U.S. Pat. No. 3,247,127, the azo dye described in U.S. Pat. No. 2,390,707, the styryl dye described in U.S. Pat. No. 2,255,077, the hemioxonol dye described in British Patent 584,609, the merocyanine dye described in U.S. Pat. No. 2,493,747, the cyanine dye described in U.S. Pat. No. 2,843,486, and the methylene type benzylidene dye described in U.S. Pat. No. 4,420,555.
When the layers containing the above dyes function as a filter layer and an anti-halation layer, the subject layers must be selectively colored while the remaining layers are not substantially colored. Particularly, if the remaining layers are substantially colored, the dye contained therein exerts a harmful spectral effect. Furthermore, the effectiveness of the filter layer and the anti-halation layer are reduced. Also, if a dye added to a specific layer for preventing irradiation diffuses to color adjacent layers, the problems as described above also arise.
A known method for solving this problem is the method in which an acidic dye having a sulfo group and a carboxyl group is localized in a specific layer with a mordant.
Known mordant agents include a polymer of an ethylenically unsaturated compound having a dialkylaminoalkyl ester residue as described in British Patent 685,475, a reaction product of polyvinylalkylketone and aminoguanidine as described in British Patent 850,281, vinylpyridine polymers and vinylpyridinium cation polymers as described in U.S. Pat. Nos. 2,548,564, 2,484,430, 3,148,061 and The cation type mordants containing secondary and tertiary amino groups, a nitrogen-containing heterocyclic group and the quaternary cationic groups thereof in polymers are used such that the above described acidic dye can be effectively mordanted.
However, when mordants are used, contact the layer containing a dye with the other hydrophilic layers often causes a portion of the dye to diffuse to adjacent layers in some circumstances. It is a matter of course that diffusion of the dye depends on the chemical structure of the mordant, and also on the chemical structure of the dye.
Furthermore, where a polymer mordant is used, staining tends to occur after photographic processing, especially rapid photographic processing, especially, in a shortened processing time. It is considered that although the bonding force of the mordant to the dye is considerably weakened in an alkaline solution such as a developing solution, some bonding force remains such that a portion of the dye or reversibly decolored product remains in the layer containing the mordant.
However, cationic type mordants tend to electrostatically interact with gelatin (often used as hydrophilic colloid) and surfactants having one of an alcolate group, a carboxylate group, a sulfonate group and a sulfate group to thereby deteriorate the coating property under some circumstances.
Furthermore, in the color light-sensitive material, cationic type mordants deteriorate the desilvering property and reduce the sensitivities of adjacent layers.
When using cationic type mordants, the above noted acidic dyes tend to diffuse to other layers. To solve this problem, use of a large quantity of the mordant was considered in order to prevent the diffusion. However, the diffusion was not completely prevented. Furthermore, the layer containing the mordant was thickened, to thereby result in a reduction of sharpness.
Furthermore, in a light-sensitive material used for printing plate making, a cutting reduction procedure is usually carried out in which a reducer solution is used to adjust the density and gradation. An involved problem is that a water soluble iron complex compound contained in this reducer solution as the reducer is electrostatically combined with the above described cationic type mordant to cause yellow stain.
These problems are solved by the dyes described in JP-A-63-280246 (the term "JP-A" as used herein means an unexamined published Japanese patent application), however, in this method desilvering is inadequate, especially when rapid processing is carried out at a low pH.
Furthermore, in a color light-sensitive material, colloidal silver has hitherto been used for absorbing yellow light and preventing halation. However, fogging of the silver halide light-sensitive emulsion layer adjacent to the layer containing the colloidal silver is increased, such that this technique also is not entirely satisfactory.
Also, a known technique is to add a dye in a dispersed solid to retain the dyes in a specific layer in a photographic light-sensitive material, as disclosed in JP-A-56-12639, JP-A-55-155350, JP-A-55-155351, JP-A-52-92716, JP-A-63-197943, JP-A-63-27838, and JP-A-64-40827, EP Patent 0015601B1 and 0276566A1, and published International Application 88/04794.
It is clear, however, that the absorption spectrum of a dye in the form of a dispersed solid is shifted as compared to the same dye dissolved in a solution or dissociated at pH 10. Furthermore, the half value width (HVW) thereof is broadened, as described in the above noted published International Application 88/04794.
While the broadening of the half value width is well adapted for filter applications in which exposure over a wide wavelength range is necessary, the overall absorption value is disadvantageously decreased. Furthermore, in a multilayer silver halide light-sensitive material, a half value width that is too broad is rather disadvantageous in the application thereof as a filter for cutting off light of an undesired wavelength in a spectral sensitivity region of a lower layer, for example, as a yellow filter or a magenta filter and the use of a dye dispersed in a solid form as a safelight filter as described in JP-A-2-110453. Also, where the dye dispersed in a solid form is used for an anti-halation layer for a light-sensitive layer having a very narrow wavelength sensitivity range, or where used for an anti-halation layer when exposing to light of a very narrow wavelength range, the dye having a low absorption value must be used in large quantity. This in turn results in disadvantages such as deteriorated decolorization, a thicker layer and increased cost.